The present disclosure relates to optical scanning devices wherein optical elements are bonded to an optical base using an adhesive and image forming apparatus equipped with such optical scanning devices.
In some copiers, printers, and other image forming apparatuses, an image is formed on a recording medium, such as paper, by an electrophotographic method. In such image forming apparatuses, an image carrier charged by a charger is scanned with light by an optical scanning device. As a result, an electrostatic latent image corresponding to image information is formed on the surface of the image carrier. The electrostatic latent image is developed by a developing device so that the electrostatic latent image is visualized as a toner image. The toner image is transferred onto the recording medium by a transfer device. The recording medium onto which the toner image has been thus transferred is transported to a fixing device. The fixing device heats and presses the recording medium so as to fix the toner image onto the recording medium. The recording medium to which the toner image has been fixed is ejected outside of the apparatus. Thus, a series of image forming operations are completed.
In the optical scanning device, light emitted from a light source such as a laser diode travels to a deflector such as a polygon mirror through a collimator lens and a cylindrical lens. Furthermore, the optical scanning device causes the light deflected by the deflector to form an image through an fθ lens so that the image carrier, such as a photoconductor drum, is scanned with the deflected light.
In the optical scanning device, in order to achieve a reduction of the number of components, maintain high optical performance, and the like, there is a securing method in which optical elements such as a collimator lens, a cylindrical lens, and an fθ lens are, for example, directly secured to an optical base with an adhesive.
However, when an optical element such as an elongated fθ lens is bonded to the optical base with an adhesive, the optical element and the optical base may be thermally expanded by temperature change occurring due to, for example, drive of the optical scanning device. When thermal expansion occurs, an excessive force is applied to a bonded portion due to the difference between the linear expansion coefficient of the optical element and that of the optical base. This leads to the occurrence of problems such as deformation or strain of the optical element or separation of the optical element.
In addition, there is a method in which an elastically deformable portion is formed in either the lens or the optical base, and the lens is secured to the optical base through the elastically deformable portion when the lens is not positioned in a vertical direction.